In general, a great quantity of CO2 is generated as a result of a pyrolysis process for collecting combustible gas and oil substances from a solid fuel and other industrial combustion processes. The CO2 is selectively removed in order to improve concentration of the collected substances.
Conventionally, a wet method has been used to capture CO2. More specifically, according to the wet method, an amine-based solution is passed through CO2-containing gas to adsorb CO2 and the solution is regenerated in a regeneration tower for reuse. However, such a wet method is disadvantageous since it additionally produces waste water.
In order to overcome the problem of the wet method, a dry method has been introduced to capture CO2. The dry method captures CO2 using two types of reactors. More specifically, CO2 supplied to a capture reactor is removed by being adsorbed on a solid adsorbent (dry adsorbent) and then the solid adsorbent is guided into the regeneration reactor to be supplied back to the capture reactor after removal of the adsorbed CO2.
An example of a CO2 capture system 1 using the dry method is disclosed in Korean Patent Registration No. 10-0527420 (dated Nov. 12, 2005). With reference to FIG. 5, the CO2 capture system 1 comprises a capture reactor 2 which captures CO2 using contact with a solid adsorbent, a cyclone 3 which receives the solid adsorbent adsorbed with CO2 of the capture reactor 2 and other gases and centrifugally separates the solid adsorbent and the gas substances from each other, and a regeneration reactor 4 which receives the solid adsorbent adsorbed with the CO2 separated by the cyclone 3 and separates CO2 from the solid adsorbent.
According to the conventional system, a fluidizing gas is supplied from a lower part to an upper part of the regeneration reactor 4 having a cylinder form so as to separate the CO2 adsorbed on the solid adsorbent. However, since the fluidizing gas is added with the separated CO2 while moving to the upper part, quantity of the moving gas is increased toward the upper part. Therefore, the pressure at the upper part of the regeneration reactor 4 becomes higher than at the lower part. Accordingly, the flow velocity of the gas gradually decreases and the separation of CO2 is not performed favorably.